Why 'Of Mice and Men'

I believe that Steinbeck called the book Of Mice and Men because because he is trying to express the idea that things can happen that you are not expecting, and you have nothing left. He is also saying that no matter how hard you work everything can be taken from you. In the poem To a Mouse a mouse has worked very hard to be able to last through the winter, and a farmer accidentally ploughs over the mouse's nest and all his work is ruined, also, because winter has come there is nothing the mouse can do to rebuild his nest because there are no twigs around and everything is frozen. In Of Mice and Men Lennie and George have been working hard their entire life to get enough money to fulfill their dream. Then Lennie accidentally kills curly's wife and they will no longer be able to work and get enough money. On top of that, George feels that it is necessary that he kills Lennie so that he/they won't get into any ore trouble. In both the book and thee poem very similar difficulties come up, and the effects are life altering.
I think by using "Of Mice and Men" as the title of the book Steinbeck is trying to say that there are traumas in every persons life and no life is an easy one; however, the people/creatures who are 'at the bottom' or are less fortunate are often effected in a more horrific way.
An example: Last year in Haiti there was a devastating earthquake (8.9), and this year there was an earthquake in Japan (8.9 and a tsunami was triggered). The earthquakes were the same size; however the one in Japan also caused a tsunami which made it 'worse'. The effects of the two earthquakes were very different though because Japan is a 1st world country and Haiti is a 3rd world country. Because the economy is not as strong in Haiti the infrastructure wasn't too strong either and building crumbled on top of people. However, in Japan buildings were built properly, and less collapsed. That is one example of how people of a lower class are effected in a harsher way by similar conflicts.